Injection rate control for fuel pumps



May 16, 1939. B. T. INSLEY 2,158,326

INJECTION RATE CONTROL FOR FUEL PUMPSv Filed May 17. 19:57 2Sheets-Sheet 1 in V V INVENTOR.

A TTORNE).

May 16, 1939. B T, [NSLEY 2,158,326

INJECTION RATE CONTROL FOR FUEL PUMPS I I Filed May 17, 1937 2 Sheets-Sheet 2 INVENTOR. 73W QT ATTORNEY.

Patented May 16, 1939 2,158,326

UNITED STATES PATENT QFFECE INJECTION RATE CONTROL FOR FUEL PUMPSBirddine T. Insley, San Francisco, Calif. Application May 17, 1937,Serial No. 142,943

3 Claims. (01. WI-53) This invention relates to a mechanism whereby acrank shaft while approaching and passing top the injection rate of thefuel delivered to the dead center. In this view, indicates the topcylinders of an engine of the compression-ignidead center position ofthe piston and the crank, tion type may be controlled. in an engine ofthe type referred to. The mech- In the operation of internal combustionenanism forming the subject matter of this appli- 5 gines, particularlyof the compression-ignition cation controls the rate or time in whichany type, the rate of injection of fuel into the comgiven quantity offuel is injected into the cylinder. bustion chamber is an importantfactor, as it af- Let it be assumed that the quantity of fuel to befects the degree of atomization and the final cominjected is one cubicinch. If that is the case, the

bustion obtained. It controls the rate of comfuel can be injected duringthe useful part of the 10 bustion, and at the same time raises or lowerscam lift during travel of the crank shaft from the firing pressure. Itprovides better control 0 to 10, or from 0 to 20, or from 0 to 30, or atof penetration of fuel into the combustion chamany point commencing at 0and ceasing or endber at different engine speeds and loads; and ing atany point between 10 and 30. In other furthermore, it permits a highrate of injection words, a given quantity of fuel can be rapidly in- 15and better atomization of the fuel at slow speeds, jected, for instance,between 0 and 10, or the rate as when starting or idling. of injectionmay be prolonged to or up to 30. The object of the present invention isto gen- Referring to the drawings, and particularly to erally improveand simplify the construction and Figs. 1 to 5, A indicates the camshaft of a Diesel 20 operation of mechanisms whereby the rate of fuel orcompression-ignition engine of the four-cycle 20 injection or thevelocity of the fuel through the type, and 2 indicates the fuel camsecured therespray nozzles may be controlled; to provide means on. Theflat face 3 is the lifting face of the cam, whereby this may beaccomplished in conjunction and this engages a cam follower in the formof a with a constant-stroke pump; to provide means roller 4 journaledbetween the outer ends of a for varying the velocity of the pump plungerdurpair of arms 5 which are pivoted to a crank 6, 25 ing the dischargestroke while the engine is in said crank being secured between two armsIl, operation; and further, to provide a mechanism the inner ends ofwhich are secured to a crank for the purpose described which isinterposed beshaft indicated by the numerals 83, said crank tween thefuel cam and the tappet of the pump shaft being provided with a lever 3which may be or the plunger proper. manually or automaticallycontrolled. The cen- 30 The invention is shown by way of illustrationter of the crank shaft 3 is located on the same in the accompanyingdrawings, in which center as the roller 4 when this assumes what willFig. l is a vertical cross-section of the mechahereinafter be termed itsneutral position, said nism taken on line II of Fig. 3; neutral positionbeing substantially its lowermost Fig. 2 is a side elevation in sectionshowing the position with relation to the heel of the fuel cam, 35device set for injecting fuel over the greatest or that position whereuniform lift or velocity range of crankshaft travel, that is, from 0 to30; commences. In order to transmit motion from Fig. 3 is a sectionsimilar to Fig. 2, showing the the roller to a tappet head H, the outerends device set for injecting the fuel in the shortest of the arms 5 areconnected by an arcuate shoe period of time, that is, between 0 and 10of crank- Ii) which rubs against the lower face of the tap- 40 shafttravel; pet head. This tappet head may be connected Fig. 4 is a viewsimilar to Fig. 2, but showing to any form of tappet l2, whereby theplunger the position of the lifting roller at the moment of a fuel pumpis actuated, or it may form a part of maximum lift; of the plungerproper. It will be noted that the Fig. 5 is a view similar to Fig. 3,said view also shoe It is curved, and that the curve is struck 46showing the position of the lifting roller at the from the center of theroller 6, and that the lower moment of maximum lift; and face of thetappet head is curved, said curve being Fig. 6 is a diagrammatic viewshowing the upstruck from a point located centrally of the cam perportion or sweep of the crank pin of a crank shaft A. By arranging theshoe on the curve 50 shaft while approaching and passing top deadspecified, and the lower face of the tappet on the 50 center. curvestruck from the center of the cam shaft, it

For the purpose of briefly stating the purpose is possible for theroller and shoe to assume difof the invention, reference will first bemade to ferent positions with relation to the tappet and Fig. 6, whichis a diagrammatic view illustrating the cam, without increasing ordecreasing the 56 the upper portion or sweep of the crank pin of lift ofthe cam; this being important, as the mechanism here shown isparticularly intended for use in connection with fuel pumps of aconstant stroke.

The crank 6 to which the arms are pivotally attached is adapted to swingthrough the are indicated at 6a, and it may swing over or through thisare between the points indicated at a and b, these points representingthe limits of movement; but during actual operation, the crank 6 may beswung by means of the lever 9 to assume any intermediate positionbetween these points.

It should be noted that the position of the roller 4, when in neutral asshown in Figs. 2 and 3, is in no way changed during the movement of thecrank 6, as the center of the shaft 8 and of the roller 4 coincide inthis position. The position of the roller when lifted from neutral tofull raised position by means of the cam is, on the other hand, verymaterially changed, as shown in Figs. 4 and 5, and it is this change inposition which determines the upward velocity of the pump plunger, or inother words the rate or speed with which the fuel is injected.

The longest period of injection, and consequently the slowest rate ofinjection, is obtained when the crank 6 assumes its lowermost positionas shown in Figs. 2 and 4. This will readily be understood when it isnoted that the roller 4, when raised by the fuel cam, swings about thecrank B in the direction of travel of the cam, and as it swings with thecam, the camwill rotate a certain distance before the maximum lift ofthe roller is reached. On the other hand, if the crank 6 assumes themaximum raised position shown in Figs. 3 and 5, the roller 4 will swingtowards the cam as it raises, and the travel of the cam will be lesswhen maximum lift of the roller 4 is reached. In Fig. 4, the rollerswings away from or to the right of a center line ee drawn through thelongitudinal axis of the tappet I2 and the center of the cam shaft A,while in Fig. 5, the roller swings towards the cam and away from thecenter line ee, but to the left thereof. Stating it in another way: inFig. 4 the lifting face of the cam is indicated by the dotted line 0,and in Fig, 5 by the dotted line d. By referring to the two dotted linepositions shown in Figs. 4 and 5, it is clearly seen that the fuel camtravels a greater distance in Fig. 4 than in Fig. 5, in order to liftthe roller 4 to its uppermost position, and as the tappet or plunger I2is actuated by the roller, the velocity of the plunger or the rate atwhich the fuel is injected may be controlled, or the time consumed toinject a given amount of fuel may be shortened or prolonged. Thus, whilethe position of the roller when in its lowermost or neutral positiondoes not change by adjustment of the crank 6, the position of the rollerdoes materially change when it is raised by the cam, as in one instance,such as shown in Fig. 4, it swings about the crank 6 in an are whichmoves away from a center line drawn through the cam shaft and thelongitudinal axis of the tappet, and to the right thereof; while in Fig.5, the roller swings in an are which causes the roller while it is beingraised to again swing away from the center line just specified, but in adirection opposite, and to the left thereof; and as the cam alwaystravels in a clockwise direction, the roller and the tappet are bound toreach their uppermost position in the least period of time when adjustedto the position shown in Fig. 5, and will require a greater period oftime to assume the uppermost position when assuming the position shownin Fig. 4. It is thus that the fuel-injecting period is shortened orprolonged, or in other words, that the velocity of the plunger or rateat which the fuel is injected is controlled.

The mechanism here illustrated permits complete injection of a givenquantity of fuel during 5 of cam shaft travel, or, in other words,during 10 of crank shaft travel; or the time of injection may beprolonged to of cam shaft, or 30 of crank shaft, travel, it beingunderstood that the fuel may be completely injected at any pointintermediate 15 and 30, by proper adjustment of the crank 5, throughmeans of the controlling lever 9. This lever may be manually controlledor adjusted during engine operation, or it may be automaticallyadjusted, as for instance by being connected with a governor or anyother suitable controlling mechanism.

The present drawings indicate a cam profile of customary commercialpractice, as this has been found to give the best average performancefor varying speeds and loads. The cam, however, should preferably beprovided with a face giving constant acceleration during the fuelinjection, and should cooperate with a fuel pump of the constant stroketype. Any standard type of fuel metering control may be employed, andany suitable form of device for advancing or retarding the point of fuelinjection may similarly be employed. While the mechanism has beendescribed in conjunction with an engine of the four-cycle type, it isobviously equally applicable to an engine of the two-cycle type; theonly change necessary would be to change the cam accordingly. Theinjection period of 0 to 30 of crank shaft travel is merelyillustrative; it may be more or less.

While certain features of the invention have been more or lessspecifically described and illustrated, I nevertheless wish itunderstood that changes may be resorted to within the scope of theappended claims, and that the materials and finish of the several partsemployed may be such as the experience and judgment of the manufacturermay dictate.

Having thus described my invention, what I claim and desire to secure byLetters Patent is as follows:

1. The combination with a rotatable fuel cam and the tappet of a fuelpump, of a cam follower actuated by the fuel cam; means carried by thefollower for imparting reciprocal movement to the tappet; an armsupporting the follower at its inner end; an adjustable support for theouter end of the arm, said follower normally assuming a predeterminedneutral position with relation to the cam when in itslowermost position;a pivot for the adjustable support, said pivot being locatedsubstantially at the same point as the center of the follower when inits neutral position; and means for swinging the support and the outerend of the follower supporting arm about said pivot whereby the followerwhen raised by the cam will move from its neutral position to a fulllift position within a greater or lesser period of time at any givenengine speed.

2. The combination with the fuel cam and the tappet of a fuel pump of acam follower interposed between the cam and the tappet, and actuated bythe cam; an arm on which said follower is carried; a pivotal support forthe opposite end of the arm, about which the arm and follower swing whenraised by the cam, said pivotal support being disposed at the outer endof a crank arm, and said crank arm being rotatable about a center whichcoincides with the center of the follower when this assumessubstantially its lowermost position with relation to the cam; and meansfor swinging the crank to change the position of the pivotal supportcarried thereby, whereby the follower and arm may swing to one side oranother of a center line drawn through the longitudinal axis of thetappet and the center of revolution of the cam.

3. The combination with the fuel cam and the tappet of a fuel pump of aroller interposed between the cam and the tappet, and actuated by thecam; an arm on which said roller is journaled; a pivotal support for theopposite end of the arm, about which the arm and roller swing whenraised by the cam, said pivotal support being disposed at the outer endof a crank arm, and said crank arm being rotatable about a center whichcoincides with the center of the roller when this assumes substantiallyits lowermost position with relation to the cam; and means for swingingthe crank to change the position of the pivotal support carried thereby.

BIRDDINE T. INSLEY.

